diff --git a/include/stdexec/execution.hpp b/include/stdexec/execution.hpp
index 7fd71c5c7..ac7609812 100644
--- a/include/stdexec/execution.hpp
+++ b/include/stdexec/execution.hpp
@@ -3072,12 +3072,6 @@ namespace stdexec {
       }
     };
 
-    template <class _Cvref, class... _Tys>
-    using __set_value_t = completion_signatures<set_value_t(__minvoke<_Cvref, _Tys>...)>;
-
-    template <class _Cvref, class _Ty>
-    using __set_error_t = completion_signatures<set_error_t(__minvoke<_Cvref, _Ty>)>;
-
     template <class _Cvref, class _CvrefSenderId, class _EnvId>
     using __completions_t = //
       __try_make_completion_signatures<
@@ -3088,8 +3082,8 @@ namespace stdexec {
         completion_signatures<
           set_error_t(__minvoke<_Cvref, std::exception_ptr>),
           set_stopped_t()>, // NOT TO SPEC
-        __mbind_front_q<__set_value_t, _Cvref>,
-        __mbind_front_q<__set_error_t, _Cvref>>;
+        __transform<_Cvref, __mcompose<__q<completion_signatures>, __qf<set_value_t>>>,
+        __transform<_Cvref, __mcompose<__q<completion_signatures>, __qf<set_error_t>>>>;
 
     template <class _Ty>
     using __clref_t = const __decay_t<_Ty>&;
@@ -3196,19 +3190,12 @@ namespace stdexec {
     struct __split_t { };
 
     struct split_t {
-      template <sender _Sender>
-        requires sender_in<_Sender, empty_env> && __decay_copyable<env_of_t<_Sender>>
-      auto operator()(_Sender&& __sndr) const {
-        auto __domain = __get_early_domain(__sndr);
-        return stdexec::transform_sender(__domain, __make_sexpr<split_t>(__(), (_Sender&&) __sndr));
-      }
-
-      template <sender _Sender, class _Env>
+      template <sender _Sender, class _Env = empty_env>
         requires sender_in<_Sender, _Env> && __decay_copyable<env_of_t<_Sender>>
-      auto operator()(_Sender&& __sndr, _Env&& __env) const {
+      auto operator()(_Sender&& __sndr, _Env&& __env = {}) const {
         auto __domain = __get_late_domain(__sndr, __env);
         return stdexec::transform_sender(
-          __domain, __make_sexpr<split_t>(__(), (_Sender&&) __sndr), (_Env&&) __env);
+          __domain, __make_sexpr<split_t>((_Env&&) __env, (_Sender&&) __sndr));
       }
 
       STDEXEC_ATTRIBUTE((always_inline)) //
@@ -3228,13 +3215,16 @@ namespace stdexec {
       template <class _CvrefSender, class _Env>
       using __receiver_t = __t<__meval<__receiver, __cvref_id<_CvrefSender>, __id<_Env>>>;
 
-      template <class _Sender, class _Env = empty_env>
-        requires sender_to<__child_of<_Sender>, __receiver_t<__child_of<_Sender>, _Env>>
-      static auto transform_sender(_Sender&& __sndr, _Env __env = {}) {
+      template <class _Sender>
+        requires sender_to<
+          __child_of<_Sender>,
+          __receiver_t<__child_of<_Sender>, __decay_t<__data_of<_Sender>>>>
+      static auto transform_sender(_Sender&& __sndr) {
         return __sexpr_apply(
-          (_Sender&&) __sndr, [&]<class _Child>(__ignore, __ignore, _Child&& __child) {
-            auto __state = __make_intrusive<__sh_state<_Child, _Env>>(
-              (_Child&&) __child, std::move(__env));
+          (_Sender&&) __sndr,
+          [&]<class _Env, class _Child>(__ignore, _Env&& __env, _Child&& __child) {
+            auto __state = __make_intrusive<__sh_state<_Child, __decay_t<_Env>>>(
+              (_Child&&) __child, (_Env&&) __env);
             return __make_sexpr<__split_t>(__data{std::move(__state)});
           });
       }
@@ -3256,12 +3246,14 @@ namespace stdexec {
     // ensure_started() is called.
     template <class _ShState>
     struct __data {
-      explicit __data(__intrusive_ptr<_ShState> __sh_state) noexcept
-        : __sh_state(std::move(__sh_state)) {
+      explicit __data(__intrusive_ptr<_ShState> __ptr) noexcept
+        : __sh_state(std::move(__ptr)) {
+        // Eagerly launch the async operation.
+        __sh_state->__start_op();
       }
 
-      __data(__data&&) = default;
-      __data& operator=(__data&&) = default;
+      __data(__data&&) noexcept = default;
+      __data& operator=(__data&&) noexcept = default;
 
       ~__data() {
         if (__sh_state != nullptr) {
@@ -3277,28 +3269,15 @@ namespace stdexec {
     struct __ensure_started_t { };
 
     struct ensure_started_t {
-      template <sender _Sender>
-        requires sender_in<_Sender, empty_env> && __decay_copyable<env_of_t<_Sender>>
-      auto operator()(_Sender&& __sndr) const {
-        if constexpr (sender_expr_for<_Sender, __ensure_started_t>) {
-          return (_Sender&&) __sndr;
-        } else {
-          auto __domain = __get_early_domain(__sndr);
-          return stdexec::transform_sender(
-            __domain, __make_sexpr<ensure_started_t>(__(), (_Sender&&) __sndr));
-        }
-        STDEXEC_UNREACHABLE();
-      }
-
-      template <sender _Sender, class _Env>
+      template <sender _Sender, class _Env = empty_env>
         requires sender_in<_Sender, _Env> && __decay_copyable<env_of_t<_Sender>>
-      auto operator()(_Sender&& __sndr, _Env&& __env) const {
+      auto operator()(_Sender&& __sndr, _Env&& __env = {}) const {
         if constexpr (sender_expr_for<_Sender, __ensure_started_t>) {
           return (_Sender&&) __sndr;
         } else {
           auto __domain = __get_late_domain(__sndr, __env);
           return stdexec::transform_sender(
-            __domain, __make_sexpr<ensure_started_t>(__(), (_Sender&&) __sndr), (_Env&&) __env);
+            __domain, __make_sexpr<ensure_started_t>((_Env&&) __env, (_Sender&&) __sndr));
         }
         STDEXEC_UNREACHABLE();
       }
@@ -3320,15 +3299,16 @@ namespace stdexec {
       template <class _CvrefSender, class _Env>
       using __receiver_t = __t<__meval<__receiver, __cvref_id<_CvrefSender>, __id<_Env>>>;
 
-      template <class _Sender, class _Env = empty_env>
-        requires sender_to<__child_of<_Sender>, __receiver_t<__child_of<_Sender>, _Env>>
-      static auto transform_sender(_Sender&& __sndr, _Env __env = {}) {
+      template <class _Sender>
+        requires sender_to<
+          __child_of<_Sender>,
+          __receiver_t<__child_of<_Sender>, __decay_t<__data_of<_Sender>>>>
+      static auto transform_sender(_Sender&& __sndr) {
         return __sexpr_apply(
-          (_Sender&&) __sndr, [&]<class _Child>(__ignore, __ignore, _Child&& __child) {
-            auto __state = __make_intrusive<__sh_state<_Child, _Env>>(
-              (_Child&&) __child, std::move(__env));
-            // Eagerly launch the async operation.
-            __state->__start_op();
+          (_Sender&&) __sndr,
+          [&]<class _Env, class _Child>(__ignore, _Env&& __env, _Child&& __child) {
+            auto __state = __make_intrusive<__sh_state<_Child, __decay_t<_Env>>>(
+              (_Child&&) __child, (_Env&&) __env);
             return __make_sexpr<__ensure_started_t>(__data{std::move(__state)});
           });
       }